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A. W. SHEPHERD. INTERNAL COMBUSTI'ON ENGINE. APPLICMION FILED Aue'. 12. i918. 1,312,585, Pacnted fmg. l2, 191).

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/l////lllmmlull/ i speed of the engine n mation in the length of stroke of the plston,

companying drawing, the main shaft ARTHUR W., SHEPHERD,

INTERNL-CGMBUSTION ENGINE.

u I Specification of Letters Patent.

oEEIoE.

or' sT. LOUIS, Missoula, AssrGNoB. or oNE-HALF To ALBERT H. HAMEL, or sT. Louis, MISSOURI.

Application led August 12, 1918. v Sex-iai No. 249,400.

To all whom it ma' concern.'

Be it known t at I, ARTHUR W. SHEP- HERD, a citizen of the UnitedA States, and a resident of the city of St. Louis and State of Missouri, have invented Ia new and use-ful Improvement in Internal-CombustionEngines, of which the following is a specification.

My invention relates to internal combustion engines and has for it-sprinclpal objects to provide for a comparatively low shaft, to provide for vato dispense with direct mechanical connection between the piston and the engine shaft, and to secure other advantages hereinafter stated. The invention consists principally in providing a cam or cams on the engine shaft in a position to receive the thrust of the pistons; it also consists in shapingsaid cams so that the piston will have a return stroke that is alternately long for scavenging and short for compression; it also consists in providing a forward stroke shorter than the power stroke so as not. to uncover the relief port; it also consists in minimizing the number of parts and in ohviating the necessity for much work of precision; it also consists in correlating the surface of the cam to the timing system so that there will be more than one complete cycle of operation of the pistons for every revolution of the engine shaft; it also consists in a mechanism for mechanically correlating the movements ofthe two pistons of a pair so as to insure the proper felation of each to the cam on the engine shaft; it also consists .in the combinations and arrangements of parts hereinafter described and claimed.

ln the accompanying drawing, wherein like reference numbers refer to like parts wherever they occur,

Figure 1 is a cross section through two cylinders of an engine. embodying my' invention; and I Fig. 2 is a fragmentary detail illustrating the tappet action by which each piston is lmade to maintain a proper mechanical relaf tion to the cam on the main sha-ft.

In the construction illustrated in the ac- 1 of the engine is journaled in a suitable framework 2', which is preferably made in the form of a horizontally splithousing 3 which completely incloses the main shaft andthe 'of repetitions. vever, that the curvature ofthe parts mounted thereon together with most of the other moving parts of the engine. Mounted on this housing are the engine cylinders 4, which are arranged radially with respect to the main shaft and preferably at an angle of 90 with Each cylinder contains a piston 5 and'is provided with an admission port 6, a release port 7, an admission valve 8, a scavenging valve 9 and with any usual type of ignition system.

Each piston is provided with a piston rod 10 pivotally connected thereto 'at one end; but instead of the outer end of the piston rod beingl pivotally connected to a crank arm on the shaft, it is pivotally connected to a link 11 which in turn is pivotally mounted on a shaft or arbor 12 mounted on the housing parallel' with the main shaft. The shafts upon which the piston rod links turn are adjacent to each other and are so disposed that the medial position of each link is .substan-- tially at right angles to the corresponding piston rod, by which arrangement the piston rod is made to have a substantially straight motion.

Mounted on the main shaft in the plane of the piston rods is a cam 13 whose periphery is formed with a major rise or peak 14 followed by a minor depression 15 and then bv a minor rise or peak 16 of less height than the rise first mentioned and then by a major depression 17 which reaches closer t0 the axis than said first mentioned depression and then by a major rise or. peak 14 of the saine height as the initial major rise or peak, and then by a depression and so on in repetition to the point of beginning. In other words,ithe pelyiphery of the cam is shaped with alternating rises and depressions, the alternate rises being respectively higher and lower land the alternate depressions being shallowerand deeper respectively for -a purpose hereinafter specified. In the construction illustrated in the drawing, one half of the periphery of the cam is a repetition of the other half; but if desired, the cam might be designed to produce even a larger number It is to be understood, howcam is .correlated With the positions and actions of the pistons and that a-change in t f repetitions of the curvatures of the cam will Patented. Aug. 12, 1919.

respect to each other.I

um1 ber of the cylinders relative to each other.

Jouinaled on a pin at the outer end of each p1ston lrod 1s a roller 18 designed for cooperation with the edge of the cam 13 on Athe main shaft and serving by co ntaet with sald cam as a means of transmitting motion alternately from the piston to the cam and 'from the cani to the piston. The parts. are

so related that when one ot the iua]o1"peaks 14 of the cam is in Contact With a roller7 the corresponding piston is at the highest osition of its stroke \vhich,'in the present instance, brings the pistfm-alinostinto contact with the head of the cylinder. This position corresponds to the stage at which explosion. Y

g head. The inletl valve has a stein 25- that.

. Each cylinder is provided with an inlet port 6r in Vits head or in its side close to the is disposed substantially parallel with the piston Yand that projects beyond the wallof the cylinder so as to terminate close to but normally out of contact withl a recipro- Aoatable rod 26 slidably mounted on the engine housing in alinementtherewith. The projecting portion of the inlet valve stem is provided with a -coil spring 27 whose ends bear respectively against the Wall of the cylinder and a shoulder'provided therefor on the valve stein, so that the spring normally holds the inlet. valve against its seat. The

inner end of the reciprocatable 'rod 264 is provided with a roller -which bears against a lever Q8 pivotally mounted on the tramework and'provided at its free endwith a roller E29 in position to cooperate with an ordinary edge cam 30 prei/ide@ for the purpose on the main shaft. the roller is relsiliently held aga-instA said earn by means of av tension springl attached to the lever for the purpose. y

The cylinder i s provided with a main relief port 7 located in the. side thereof in position to be uncovered` by the piston as it approaches the limit of. its forward ower stroke. Inaddition to this main relie port, each cylinder is providedwith a scavenging port 23 located in fthe hea-d `thereof (or in th'side wall close to said head) and controlled by a suitable valve 9. In the con-J struction illustrated in the drawing, the scavenging valve 9 is seated in the valve seat provided thereforin a passageway 24 leadingfrom the scavenging port and open ing into the atmosphere. This scavenging vport'is controlled by a valvel that. opens' inwardly/.into .the cylinderA :17nd ,has a are;

ciproeating stern 19 extending through the i ,tact with the cani on' the main shaft.

0n' the pivot pins of said links cylinder head. The valve stem is provided with a coil spring 20 whose ends bear lagainst the cylinder head and against a shoulder on the valve stem respectively so as to normally hold said valve against its seat. Any Suitable device of known type may be used lor actuating this valve. For instance, a lever 21 mounted on the cylinder has one arm arranged to actuate the' valve stem and the other arm operatively connected by a rod-22 provided with a Contact roller to a suitable cam 37 on the n ain shaft to be actuated thereby.

The relation of the several parts just mentioned is such that when the piston is on its long return stroke7 the cam 37 will move the lever arm 28, Whose movement is communicated through the reciprocatable rod 22 and lever Q1 to the scavenging valve 9, thereby opening the passage-Way through the scavenging port in the head of the Cylinder. The scavenging passage-way remains open until the piston reaches the limit. of its long return stroke. whereupon the lever and reciprocatable rod resume their normal positions and the spring holds the scavenging valve to its seat. At. this stage. the charg-i ing valve opens simultaneouslfl' With the forward stroke of the piston to admit the charge into the cylinder.

The following special provision is made for maintaining the piston rod rollers in conis stated above. the links l1 at the ends of the, piston rods are pivotcd close to 'each other.

pivotally mounted members $1, that serve as extensions for the respective links. .Eachof these extension members' is provided with a fork or bifurcated portion 83 which straddles the corresponding link. The throat or spread of the fork is Wider than the link so as to ati'ord play or lost motion between the link and said member. One leg of-the fork is provided with an adjustable bolt on irhich is mounted a coi'lspring 3l whose ends bear against the link `and one leg of the cxten sion member' respectively. Theouter end 0i 'one of )the members 31 is itself bifurcated and provided with bearing rollers 35, 36.

lier

The outer end of the other member 32 prbjectsbetween said rollers and its. opposite ed'ges are curved in such form that both edges will continue in Contact.' with the corresponding rollers at all times. -This arrangement constitutes a yielding or resilient mechanical connection between the two links so that motion and power maybe transmitted from one'to the other as occasion `may require, as when the engine is being started.

VThe general operation of ,the 'machine is common features as the timing and ignition features andthe like. In the position illus- .trated in Fig. v 1, the left hand cylinder is charged and ready to tire and the. right hand cylinder has completed its scavenging action preparatory to receiving a new charge. The piston rod roller of the left hand cylinder is at the crest of the minor peak of the cam;A

and when the explosion occurs, the piston moves forward and the power i# transmitted therefrom through the piston rod and the' roller thereon against the edge of the cam.

While the stroke of the piston is radial with tween the pitch circle at thel crest of the minor peak of the camV and the pitch circle of the lowest point of the depression being the length of the eiiective piston stroke. Throughout its forward stroke, the pressure of the iston is effective to turn the cam. When the piston is at the forward limit of its stroke, the pressure therein is relieved through the relief port in the fore part ofl the cylinder which is uncovered in this position of the piston. The continued movement of the cam is transmitted to the piston and effects the return stroke of the piston. It is noted that this return movement .of the piston is eii'ected by the portion of the cam curve that begins at the bottom of a major depression and terminates at the crest of a major peak. As this major peak extends fart-her from the axis of thc shaft than the minor peak, it causes the return stroke of the piston to be longer than the forward power stroke thereof. The purpose of this long return stroke is to thoroughly scavenge the cylinder and this action is aided by locating the scavenging port in the cylinder head. At the end of this scavenging stroke, the piston is `in the position indicated at the right hand .in Fig. l.

The forward movement of the piston from the Aposition illustrated in Fig. 1

is effected through its mechanical connection with the piston of the other cylinder of the pair. Thus. referring to the positions indicated in Fig. 1, the forward movement of the left hand piston causes the link that is connected thereto to rock the extending yoke thereon and the roller on the lower arm of the extension bears against the under surface of the extension of the link connected to the piston rod of the right hand piston. By this arrangement, the forward or downward fmovement'of the left hand piston is transmitted ton-the right handvpiston to effect a forward and downward'movement thereof.

During this'l forwa rd stroke of the right' hand piston, it receives its charge and at the limit of its forward stroke its roller is in contact with the cam at the lowcrmost point ot its minor depression. lt is noted that the forward limit ot this forward stiroke is enough short of the limit ot the power stroke to keep the relie]c port from becoming uncovered by the piston. As the cam continues to revolve, it bears against said roller and eifects the return stroke of the piston until it reaches the crest ot' the minor peak corresponding to the position illustrated in Fig. l. During this return stroke, the charge has been compressed and is vready for explosion, both pistons having completed their complete cycle of operation. while the shaft has made one half a revolution;

One of the great advantages of my invention is the fewness of its parts and the great simplicity-.of its organization. Thus, the valve mechanism is reduced to a minimum 'and that of thc simplest-form; in fact, the

usual relief valve is dispensed with entirely. The contact connection between the piston and the shaft is ot' a very simple character and permits the piston to transmit a plurality of torque efforts for each revolution of the shaft; and the speed of the engine shaft is small compared withthe speed of the piston. Also the speed of the engine can be controlled considerably hy modifications of the cam. For instance, the forward or power stroke of the piston is eii'ective throughout the angle that lies between 'the minor peak and the major depression; and by varying this angle, the relation of the speed ot the piston to that of the engine is likewise varied. ,A convenient way of modifying this angle is to vary the rises o the cam itself, with corresponding variations, of course, in the angular positions of. the cylinders.

Obviously. the construction illustrated in the accompanying drawing admits of considerable modification without departing from my invention and I do not wish to be restricted tothe exact construction shown.

7Whait l claim is:

l. An internal combustion engine comprising Ia main shaft., a cam thereon, a plurality of cylihders disposed radially about said slraiit, pistohs in said cylinders and piston rods pivotal-ly connected tosaid pistons at one end and having operative contact engagement withl said cam yart their otherv end,

the curvature of said cam comprising a major peak, a. minor depression, and a major depression.

2. An internal combustion engine' oomprising a main shaft, a cam thereon, ay plurality of cylinders disposed radially about said shaiit, pistons fin said ders and piston rods pivotally o'onneca to said pistons at one end andhaving operative contact ena minor peak glagexnentp-with said cme attheirother end,

the curvature of cam comprising repe- 'ti'tions of a curve consisting of e majorpenk,

a. minor depression, a minor peak and a major depression.

3. An internal combustion engine comprising a main shaft, e cemthereon, a plurality of cylinders disposed redially about said shaft in a. common plane, pistons in said cylinders and piston rods pivotally connected to said pistons at one end and operatively enga-ging said cam .alt their other end, the curvature of said cani comprising a major peak and la. minor peak arranged to bein alinemenrt simultaneously with the respective cylinders. l

Il. A four-cycle internal combustion engine comprising' a main shaft, e. cam thereon, e plurality of cylinders disposed radially about said shaft, pislnns in said cylinders and piston rods pivotally connected tol said pistons at one end and operatively engaging said cam at their other end, said earn comprising repetitions of .a curve consisting of a ma- 'jor peak corresponding to the scavenging stroke, a minor depression corresponding to the charging stroke, a minor peak corresponding to the compression stroke and a major depression corresponding'to the power stroke, said cylinders having inlet and' scavenging ports at or near the heads thereof and ha ving their relief ports in the fore part in position to afford relief only' when the piston near the forward limit of its power4 stroke and the cylinders heinor so disposed as to loe 'in simultaneous alinelnent with a Inajor and a'minor peak respectively.

5. In an' internal combustion engine, a main shaft, a cani thereon, explosion cylinders radially disposed with respect to the shaft and angular-ly disposed with respect to each other, pistons in said cylinders, piston rods pivotally connected fto said pistons and having their 'outer ends nrranged for cooperation with said carni by mere Contact therewith, links pivotally mounted on the framework adjacent [to each other andpivotally connected to the outer pontionsof said piston rods respectively, and cooperating extensions on said links for coordinating the motions of said links and thereby inra-inteining operative `contact of vsaid piston rods with said cam..

6. In an engine of the kind described, a main shaft, a cam thereon, explosion cylin'. ders radially disposed with respect to the shaft land :angularly'disposed with respect to each other, pistons in .said cylinders, piston nods pivota-lly connected to said pistons and having their outer ends arranged for copenatlon with said cam 'by mere Contact there- .Wirtin-links pivotally mounted on the framel work adjacent each other and pivotally connected to the outer portions of said piston rods respectively, and coperating extensions on lsaid links for coordinating the motions of said links and thereby maintain- 7. In an internal cornloustion engine, a. y

main shaft, a. cam thereon having major and minor peaks separated by depressions, explion cylinders radially disposed with respect te the shaft and angularly disposed with respect .to each other, pistons 1n said cylinders, "piston rods pfivotally connected to said pistons and having their outer ends arranged iior copereition with said cam, links ypivotally mounted on fthe framework adjacent to each other and pivotally 'connected to the outer portions of 'said piston rods respectively, and coperating extensions on said links for coordinating the motions of said links, said extensions being yieldably mounted, one of said extensions' comprising a bifurcarted member having one arm which normally clears the' cam, but which extends across the patlh of the major peak of said cam When the corresponding piston is at the end of its return stroke;

8. An interna-l combustion engine com# A prising an explosion cylinder having 'a charging port `at or near rthe head and a scavenging port at ornear the hea/d and a. relief port in the fore `part offthe cylinder, and 'a piston in smid cylinder Whose forward stroke alternately passes and falls short of said relief port and whose return stroke is altern'ately oli' full length for scavenging and of shorter length for compression.-

9. An engi-ne of the class described comprising n cylinder having a. relief pont in-its fore-pant, a. piston insaid cylinder and means for vvarying Ithe stroke of said piston' so that on each -aliternate stroke said piston uncovers the relief port While on each intermediate stroke fthe piston keeps said `port covered.

10. ln an engine of the class described, a

adapted yto open and keep open the soavenging valve until the-piston reaches the limit valve.

day of August, 1918.

i ARTHUR W; SHEPHERD.

signed 'at st. nous, aus nh 12oy of its long return stroke 'then to close said `scavenging valveand open the inlet 

